| Answer | Crossword Clue |
|---|---|
| philosophical | Devoted to the study of such issues |
| tribology | the study of interacting surfaces in relative motion and associated issues, such as friction, lubrication, and wear |
| tribologies | TRIBOLOGY, the study of interacting surfaces in relative motion and associated issues, such as friction, lubrication, and wear |
| litterateur | (French) one who is devoted to the study or writing of literature |
| litterateurs | LITTERATEUR, (French) one who is devoted to the study or writing of literature |
| economic | pertaining to the study of such a system |
